However, the always-gorgeous star did undergo a dramatic physical transformation for her role in Gimme Shelter (out in theaters Jan. 24), where she plays Apple, a homeless 16-year-old mother-to-be who finds help at a suburban shelter. Directed by Ron Krauss, the movie also stars Rosario Dawson as Apple's mom and Brendan Fraser as her dad, a rich Wall Street man she's never met.

"It was fun, it was really fun. Just because its so rare that you get to do that. I put on 15 pounds, ate whatever I wanted. I'm not complaining. I cut off all my hair, which really set the tone. It was such a liberating thing and kinda reminded me—if I can do that, I can do this," Hudgens told E! News of her transformation.

"And then, I just kinda tried to make myself as ugly as possible, whether that was the way that I walked or my mannerisms or the tone of my voice. I wanted her to be strong and tough but broken because that's what she is. You just see her transform into someone who actually finds love and really feels it for the first time and there's nothing more powerful than finding love."

The High School Musical star admitted taking the weight off afterward was tough, but not as tough as breaking away from character.

"I think I unconsciously stayed in character the entire time that we were filming, so soon as we were done, I didn't know how to act anymore, because I was so used to playing Apple. She was my security shield. I had to work really hard at finding myself again," Hudgens confessed, and added that her struggle with letting Apple go alerted her friends and family.

"My best friend tells me all the time how she was so concerned about me, because, she, for the first time, looked into my eyes and she didn't see me. She saw someone who was really broken down and had very low self-esteem. So it took a lot of work. It was good because it made me that much stronger and I have to give myself a pat on the back for going that deep."

Luckily, Vanessa was able to get herself together just in time to help her bestie Ashley Tisdale plan her wedding. "She's got a good idea of what she wants to do," Hudgens tells us. "I think we're gonna go shopping for dresses soon, which I'm very excited about!"

—Reporting by Will Marfuggi

For more on this interview, tune in to E! News tonight at 7 p.m. & 11:30 p.m.